On 9/8/12 at 3:09 AM, zerge69 at gmail.com (Sergio Sergio) wrote:
>Hi, does anybody know how to count elements within a matrix? I know
>how that Count works for lists, but it does not seem to work for a
>matrix. Any tips?
It would be easier to make useful suggestions if you would
provide more details of what you want to do. Meanwhile, here are
some ideas:
use the third argument of Count,
In[1]:= m = RandomInteger[10, {20, 20}];
In[2]:= Count[m, 2, 2]
Out[2]= 32
Use Flatten with Count
In[1]:= m = RandomInteger[10, {20, 20}];
In[2]:= Count[m, 2, 2]
Out[2]= 32
Use Total with Count
In[4]:= Total[Count[#, 2] & /@ m]
Out[4]= 32
Or for something that doesn't use pattern matching and is likely
much faster for some applications
In[5]:= Total[1 - Unitize[m - 2], 2]
Out[5]= 32